1. Field of the Invention
The present invention relates to an image recording apparatus used for image copying and printing operation. More particularly the present invention relates to an image recording apparatus of a type employed with a particle controller having apertures for controlling flow of toner particles passing through the apertures to record a toner image on an image recording medium.
2. Description of Related Art
U.S. Pat. No. 3,689,935 has proposed an image recording apparatus of a type that has a source of electrically-charged coloring particles such as toner particles, a control electrode (which will be referred to as "a particle controller," hereinafter) having apertures for selectively allowing the toner particles to pass therethrough, and a back electrode roller. The particle controller includes a reference electrode, an insulative layer formed on the reference electrode, and a plurality of segmented control electrodes formed on the insulative layer. A plurality of apertures are formed in the particle controller so as to penetrate through the reference electrode, the insulative layer, and the segmented control electrodes at overlapping areas of the segmented control electrodes and the reference electrode. When the source of the electrically-charged toner particles supplies the electrically-charged toner particles to the reference electrode of the particle controller, the particle controller selectively allows the toner particles to pass through the apertures. The back electrode roller is electrically charged to have a polarity opposite to that of the electrically-charged toner particles. The toner particles which have passed through the apertures of the particle controller are therefore electrostatically attracted toward the back electrode roller. In other words, the toner particles that are modulated by the particle controller are attracted by and flow in the direction of the static electrical force produced by the back electrode roller. The toner particles then adhere to the image recording medium which passes between the particle controller and the back electrode roller, thus forming a toner image thereon.
When an image is recorded using the above image recording apparatus, however, a problem occurs in that toner particles clog the apertures of the particle controller.
A co-pending U.S. patent application U.S. Ser. No. 680,728 abandoned, has proposed one method for overcoming this problem in which an oscillating member is attached to the particle controller for vibrating the particle controller to shake loose the toner particles attached to the inner surface of the apertures of the particle controller. The image recording apparatus of the co-pending application has successfully improved image clarity.
Another co-pending U.S. patent application U.S. Ser. No. 781,416, U.S. Pat. No. 5,202,704 issued Apr. 13, 1993 has proposed another method for overcoming the above-described problem in which the oscillating member is indirectly attached to the particle controller. More specifically, the particle controller is provided with an elastic member which is attached to the oscillating member. The oscillating member produces ultrasonic waves to be propagated through the elastic member to the particle controller, so that the toner particles are shaken off from the particle controller.